Pages

Oct 26, 2006

So we've given you a sneak peak of the many species of seagrasses found in Singapore waters and we've got the FAQs covered, save perhaps, THE most frequently asked question:

What on earth is a seagrass?

Seagrasses are marine flowering plants and are sometimes better known as dugong feed. They are often mistaken for seaweed or algae. However, unlike algae, seagrasses are unique in that they have flowers, bear fruit and produce seeds. Seagrasses complete their entire life-cycle immersed in water, with the exception of Enhalus, which must emerge to the surface of the water to reproduce.

Seagrasses also have a system of roots (rhizomes), stems and leaves, which are used for various functions including anchoring, photosyntheis (food production) and transport of nutrients and energy. They are often found growing in sandy or muddy substrates from which they obtain their nutrients. This is unlike algae, which derives its nutrients directly from the water column.

Although they can look very similar to their terrestrial namesakes, seagrasses are actually more closely related to lilies and gingers than to the grasses found on land.

More about seagrasses

Seagrasses are found in a range of coastal habitats, but Seagrass meadows are typically found in shallow, soft-bottomed areas. In Singapore, Chek Jawa (on Pulau Ubin) and Pulau Semakau have by far, the largest meadows with the highest diversity of seagrasses.

The different species of seagrasses favour different growth conditions. For example, Halophila ovalis (spoon seagrass) grows pretty much everywhere in Singapore. They're very hardy and often all it takes for them to grow is seawater, sand and not too much wave action. However, these often scoffed at little guys (they are often met on recce trips with a "Aiyah... ovalis again?") pave the way for other species of seagrasses to colonise the area because they improve surrounding conditions by stabalizing and increasing Nitrogen availability in the sediment.

On the other hand, we have Enhalus acoroides (tall tape/ribbon seagrass) which prefers harder areas (by harder, I mean you don't sink in and fall on your behind... as much) and are often found in small clumps in between coral rubble (on the far side of Chek Jawa) or on rocky shores (Labrador Beach and Sentosa).

Ask not what the seagrasses can do for you, but what YOU can do for the seagrasses

Not convinced you should help out? Well what if I tell you that seagrasses are extremely useful and productive habitats? In addition to stabalising coastal sediment, seagrass meadows on reef flats and near estuaries act as a buffer zone, filtering nutrient and chemical input into the marine environment. They also provide food, shelter and nursery grounds for a vast variety of organisms including molluscs, crustaceans (prawns, shrimp and crabs) and fishes (both the kind you eat (commercial species) and the kind you like looking at (reef fishes)).

Long term monitoring of seagrass habitats helps us understand the dynamics of these habitats and whether changes in distribution, cover and species composition are part of a natural process or the result of human influence. Data from regular monitoring also helps in coastal management.

So what can you do for our local seagrasses? Join team seagrass! You're guaranteed lots of fresh air, salt water, laughs and memories to last you if not a lifetime, then at least till the next monitoring session.

That's right! Johor Baru just across the Straits! In the photo is Len McKenzie (in light blue) from Seagrass-Watch HQ. Next to him is Choo Chee Kuang, who has been working relentlessly on seahorse conservation in Malaysia. More about Choo Chee Kuang and the seahorses on his Save our Seahorses website

Oct 25, 2006

Several fascinating species of seagrasses grow on our shores. Here's a quick introduction to all the species that can be found in Singapore.Tape seagrass (Enhalus acoroides) is the longest seagrass found on our shores. The leaf blade is 1-2cm wide and can be 1.5m long! Pulau Semakau has vast tracts of Tape seagrass meadows that stretch for kilometres!

Male flowers of the Tape seagrass are tiny (see the small white bits?). They form in a bract that grows at the base of the plant. During a bloom of Tape seagrass, little 'rafts' of male flowers are often seen floating on the water. They look like little bits of styrofoam!

Female flowers are large and emerge on long coiled stalks. The pale yellowish petals last only for a day or so. Often, all that is seen are the V-shaped bracts. Soon, the large fruit develops. It is a hairy capsule that holds several seeds. The seeds are said to be edible and are eaten by some coastal dwellers. The raw seeds are said to taste like chestnuts.

There are several species of Halophila seagrasses. Some have oval leaves and thus called Spoon seagrasses. The various species of oval-shaped Halophila are difficult to differentiate in the field, so all of them are generally referred to as Halophila ovalis complex. These seagrasses are the most commonly encountered on many of our shores.

The beautiful Fern seagrass (Halophila spinulosa) is made up of many little leaflets. Usually a bright green, sometimes with a bluish tint, this seagrass is widespread on Chek Jawa.

Singapore is home to the delicate Beccarri's seagrass (Halophila beccarrii). The tiny leaves of this seagrass emerges in a rosette of 4-5 leaves. Elsewhere in the world, this seagrass is considered rare. But it is quite commonly seen on Chek Jawa.

There is a large patch of ribbon seagrass (Cymodocea rotundata) on Chek Jawa. This elegant seagrass is narrower and not as long as Tape seagrass.Needle seagrass (Halodule sp.) is long, narrow and well, needle-like. On Chek Jawa they are lush and long. Elsewhere, they may be much shorter.

Sickle seagrass (Thalassia hemprichii) is indeed sickle-shaped. A lush meadow of this seagrass grows on Labrador, the last on our mainland.

Sickle seagrass has little flowers with curly 'whiskers'.

Syringodium isoetifolium is a strange seagrass. Its leaf blade is cylindrical, like plastic tubing! It is commonly seen (so far) only on Pulau Semakau.

Our job for Seagrass Watch is to look out for all these wonderful plants on our shores. And to monitor their growth.

Why watch seagrasses?!

It MAY seem dead boring to literally watch grass grow. But when it's seagrasses it can get really wild and wacky! Here's the adventures of a team of volunteers keeping a watch on Singapore's amazing marine meadows. As well as seagrassy news. More about Singapore's seagrasses and how to join the Team!